Practical in situ-generation of phosphinite ligands for palladium-catalyzed carbonylation of (hetero) aryl bromides forming esters

An effective method for alkoxycarbonylation of (hetero) aryl bromides is developed in the presence of in situ-generated phosphinite ligands (Bu2POR)-Bu-t (R = Bu-n, Pr-n, Et or Me). For this purpose commercially available (Bu2PCl)-Bu-t was used as the pre-ligand in the presence of different alcohols. For the first time cross coupling reactions with two alcohols - one generating the ligand, the other used as substrate - were developed. Through this method, ligand optimization can be performed in a more efficient manner and the desired products could be obtained with good yields and selectivity.